Worldwide terror threats are more increasing. In recent years, methods of manufacturing explosives using articles of daily use are widely known, and terror and crime owing to the explosive also become threats to our daily life. Multiple acts of terror were reported in London, causing many casualties. In addition, a suspect who has planned the suicide bombing at a commuter train was reportedly arrested in Japan.
In order to prevent the terror or the crime beforehand, techniques of sensing dangerous substances are developed in various countries. For example, patent document 1[JP-A-2000-28579] disclose an explosive sensing device using a mass spectrometer. Vapors leaked from a baggage are collected by a sampling probe, are ionized using a negative corona discharge, and are detected using a mass spectrometer, thereby determining whether a dangerous substance is present.
A technique of using a mass spectrometer as a detecting section of a security system to enhance an inspection speed or test reliability is disclosed in patent document 2[JP-A-2003-14695]. This security system transmits a signal obtained in an analysis unit (a terminal system) to an assist system via a communication line, and the assist system determines whether a dangerous substance is present. The determination result of the assist system is transmitted to the terminal system via the communication line. By doing so, an operator manipulating the terminal system does not need to have a special knowledge or training.
In addition, a system for sensing an intrusion of a suspicious person is disclosed as an example of security device in patent document 3[JP-A-2005-122634]. According to this security device, a person detection sensor outputs an alarming trigger when the detection having the detection number not less than a predetermined value is continuously carried out for a predetermined time. By doing so, a recording amount of a security camera is not unnecessarily increased even at a building such as an apartment where many people come and go.